Glue preparation and product



@atented Jan. 31, 19:33

unrran STATES nnwnnn r. CHRISTOPHER AND FRANK L. :on nnnnnnann, or onicneo, rumors, ASSIGNOBS ro swim & COMPANY, or cnrcaeo, ILLINOIS, A oonrona'rion or ILLINOIS GLUE PREPARATION AND PRODUCT Itl'e Drawing.

This invention relates to a process by which the action of formaldehyde on glue and gelatin products may be controlled within sharp limits and throughout a wide range of temperatures. This invention also relates to a process by which glue and gelatin may be reclaimed for further use from its insoluble stage after being rendered insoluble either intentionally or accidentally by the action of formaldehyde.

It is well known that glue and gelatin possess the characteristic of undergoing a reversible physical change between the sol and gel phases, and that one of the best methods for rendering irreversible this characteristic change is that of treating the dispersed glue or gelatin with some form of formaldehyde. This reaction with formaldehyde possesses many practical advantages, and is of considerable industrial importance in that it is extensively employed in those cases where water resistance is required in products fabricated by the use of glue or gelatin. Notwithstandin the importance of this known reactionof ormaldehyde on glue and glue prodnets in commercial practice, considerable difficulty is inherent in the use thereof due to the inability, prior to this invention, to control or retard the action of the formaldehyde. It is known that some methods have been proposed for increasing the working life of gelatin formaldehyde mixtures, but as far as the applicant knows, these have proven ineffective, unreliable and impractical.

Accordingly, the present invention is based upon the discovery of a method by which the known action of formaldehyde on glue and gelatin products may be controlled and retarded so that the'working life of such products may be increased and a higher degree of success may be realized in the use of formaldehyde with glue and gelatin products. Also glue which has already become insoluble b the action of formaldehyde may be reclaime for further use by means of the process of this invention.

It has been found that urea or products derived from urea either byheat or mechanical mixture, when permitted vto react with the glue or gelatin, produce a retarding effect on Application filed July 13,

the action of formaldehyde and thereby permits one to control the predetermined working life of mixtures of glue or gelatin and formaldehyde within sharp limits and throughout a relatively wide range of temperatures. The amount of urea employed in any particular instance will Vary according to several factorsand depending upon the particular results desired. In practice, it is found that the characteristic effect of the urea is increased substantially proportionally to the quantity of urea employed, and therefore the other prevailing conditions should be considered, such as the nature of the glue being treated, the temperature at which the mix TS to be held, the magnitude of the working life period desired, the amount of formaldehyde present and the hydrogen ion concentration of the mixture.

As set forth in the applicants co-pending application Serial No. 550,618 filed July 13, 1931 entitled Preparation of glue and the product thereof it is now known that the setting temperature for any particular glue is lowered directly proportionally to the increasing amount of urea used. In practice 7 it is preferable first to dissolve the desired quantity of urea in water which may then be added directly to the glue or gelatin to be treated. lln like manner glue which has been rendered insoluble by the action of formal dehyde may be rendered soluble once more ble glue or gelatin soluble bythe action of urea.

. Signed at Chicago, in the county of Cook and State of Illinois, this 10th day of July,

1931. EDWARD F. CHRISTOPHER. FRANK L. DE BEUICELAE'R. 

